EPC Ratings Explained — A to G Scale, Scores & What They Mean

Every Energy Performance Certificate in the UK assigns a property a rating from A (most efficient) to G (least efficient). This rating is based on the property's Energy Efficiency Rating (EER) — a numerical score from 1 to 100. The higher the number, the more energy-efficient the property.

Rating System Changes:

From H2 2027, new EPC certificates will use the Home Energy Model (HEM) with four separate metrics instead of a single A-G band. Current A-G certificates remain valid for their full 10-year term.

The A–G Rating Bands

Rating	Score Range	What It Means
A	92–100	Exceptionally efficient. Rare in existing homes — mostly new builds to the highest standard. Very low energy bills.
B	81–91	Highly efficient. Modern new builds and heavily retrofitted older properties. Annual energy costs well below average.
C	69–80	Above average. The incoming minimum standard for rental properties by 2030. Well-insulated with a modern heating system.
D	55–68	The most common rating in England and Wales. A typical 1950s–1990s house with some insulation and a gas boiler.
E	39–54	Below average. The current legal minimum for rental properties. Older properties with limited insulation.
F	21–38	Poor efficiency. Illegal to let without an exemption. High energy bills, typically pre-1930s construction.
G	1–20	Worst performing. Illegal to let. Often uninsulated solid-wall properties with outdated heating systems.

Current Rating vs Potential Rating

Every EPC shows two ratings: current and potential. The current rating reflects the property as it stands today. The potential rating shows what it could achieve if all recommended improvements were carried out.

For landlords, the gap between current and potential is particularly important — it shows how far the property could improve and at what cost. A property rated D with a potential of B, for example, has a clear upgrade pathway that may be achievable within the £10,000 cost cap.

What Rating Do Most UK Properties Have?

The average EPC rating in England and Wales is D (score around 60). The distribution looks roughly like this:

A or B: ~15% of properties (mostly post-2010 new builds)
C: ~30% of properties
D: ~35% of properties — the largest single group
E: ~14% of properties
F or G: ~6% of properties

For the private rented sector, approximately 52% of properties are currently below EPC C — meaning over 2 million rented homes need upgrading before the 2030 deadline.

EPC Rating C — The 2030 Target

EPC C (score 69–80) is the incoming minimum standard for all privately rented properties in England and Wales by 1 October 2030. A typical EPC C property has:

Adequate loft insulation (270mm+)
Cavity wall insulation or well-insulated solid walls
Double glazing throughout
A modern condensing boiler or heat pump
Low-energy lighting

For many landlords with D-rated properties, reaching C is achievable with targeted improvements costing £1,000–£4,000.

EPC Rating D — The Most Common Rating

EPC D (score 55–68) is where the majority of UK housing stock sits. These are typically 1950s–1990s properties with partial insulation and standard gas boilers. The gap from D to C usually requires loft insulation, cavity wall insulation, and LED lighting as a minimum.

EPC Ratings E, F, and G — Legal Implications for Landlords

EPC E (39–54) is the current legal minimum for rental properties. Landlords can legally let a property at E but not below. Properties rated F or G cannot be let without a registered exemption, and fines for non-compliance reach up to £30,000.

The New Home Energy Model (HEM) — Coming H2 2027

The single A–G band is being supplemented (and eventually replaced for new certificates) by four new metrics under the Home Energy Model:

1. Fabric Performance

How well the building retains heat, measured through:

Heat Loss Parameter: Overall thermal performance
Air Permeability: How airtight the building envelope is
Thermal Bridging: Heat loss through structural elements
Rated A-E: Similar to current system but fabric-specific

2. Heating System Efficiency

The efficiency and environmental impact of heating and hot water:

Seasonal Efficiency: Real-world performance across the year
Carbon Intensity: Environmental impact per kWh
Fuel Source: Gas, electricity, renewable, etc.
Rated A-E: Heat pumps typically A/B, gas boilers C/D

3. Smart Readiness Indicator

The building's capability to adopt smart technology:

Smart Heating Controls: Programmable, zone control, weather compensation
Energy Management: Smart meters, in-home displays, energy apps
EV Readiness: Electric vehicle charging infrastructure
Renewable Integration: Solar panel compatibility, battery storage
Rated 0-100%: Percentage of smart-ready features present

4. Energy Cost Indicator

Estimated annual running costs based on standardized usage:

Heating Costs: Space and water heating
Electricity Costs: Lighting, appliances, auxiliaries
Standing Charges: Fixed daily/monthly fees
Total Annual Cost: In £ per year for average occupancy

HEM vs Current EPC Comparison

Current EPC (SAP)	New HEM System
Single A-G rating	Four separate metrics
Based on CO₂ emissions	Based on actual energy performance
Static assessment	Considers smart technology potential
Theoretical energy use	More realistic running costs
Valid 10 years	Valid 10 years (same validity period)

What This Means for Property Owners

Current EPCs remain valid: No need to rush for new assessment
More detailed information: Better understanding of where to invest
Future-proofing focus: Smart readiness becomes important
Clearer cost estimates: More accurate running cost projections
Fabric-first approach: Insulation and airtightness emphasized

Key Takeaway

The current A-G system remains the legal standard until at least 2030. HEM introduces more nuanced assessment but doesn't change existing legal requirements. Properties still need to meet EPC C by 2030 for rental compliance.

EPC Ratings Explained — The A to G Scale